Write a Python function that checks whether a passed string is palindrome or not

I have used python 3.7 compiler for debugging purpose.

def isPalindrome(string):
    left_pos = 0
    right_pos = len(string) - 1
 
    while right_pos >= left_pos:
        if not string[left_pos] == string[right_pos]:
            return False
        left_pos += 1
        right_pos -= 1
    return True
print(isPalindrome('12121'))

Result:

True